Historically two industrial processes have been used for the production of vinyl chloride monomer. A good overview of this activity is given in Kirk-Othmer, Encyclopedia of Chemical Technology, 4th ed., Vol. 24, pp. 872–875. The first general method for the preparation of VCM involved the addition of hydrogen chloride to acetylene to give vinyl chloride directly. Newer processes that rely on ethylene as a raw material have now largely supplanted this process. Using one of several methods, ethylene is converted to ethylene dichloride (EDC), which is thermally cracked to produce VCM and byproduct hydrogen chloride. By recycling the hydrogen chloride, balanced processes are achieved.
Because ethylene comprises about 45 weight percent of VCM, the cost of ethylene is a major factor in the manufacturing cost. As a result, there exists an interest to find a less expensive hydrocarbon raw material. The most likely candidates are ethane and methane, but so far, attempts have been frustrated by the relative inactivity of these two hydrocarbons.
Therefore, it is an object of the present invention to substitute a cheaper source of hydrocarbon for ethylene in the manufacture of VCM. Another object is to provide a method that gives high yields of product. These and other objects, features and advantages will be apparent from the following description.